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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * accompanied this code).
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package com.sun.awt;

import java.awt.*;

import sun.awt.AWTAccessor;
import sun.awt.SunToolkit;


A collection of utility methods for AWT.
The functionality provided by the static methods of the class includes:

    

  • Setting shapes on top-level windows

  • Setting a constant alpha value for each pixel of a top-level window

  • Making a window non-opaque, after that it paints only explicitly
painted pixels on the screen, with arbitrary alpha values for every pixel.

  • Setting a 'mixing-cutout' shape for a component.



 A "top-level window" is an instance of the Window class (or its descendant, such as JFrame). 
 Some of the mentioned features may not be supported by the native platform. To determine whether a particular feature is supported, the user must use the isTranslucencySupported() method of the class passing a desired translucency kind (a member of the Translucency enum) as an argument. 
 The per-pixel alpha feature also requires the user to create her/his windows using a translucency-capable graphics configuration. The isTranslucencyCapable() method must be used to verify whether any given GraphicsConfiguration supports the trasnlcency effects. 

WARNING: This class is an implementation detail and only meant
for limited use outside of the core platform. This API may change
drastically between update release, and it may even be
removed or be moved in some other package(s)/class(es).

/**
 * A collection of utility methods for AWT.
 *
 * The functionality provided by the static methods of the class includes:
 * <ul>
 * <li>Setting shapes on top-level windows
 * <li>Setting a constant alpha value for each pixel of a top-level window
 * <li>Making a window non-opaque, after that it paints only explicitly
 * painted pixels on the screen, with arbitrary alpha values for every pixel.
 * <li>Setting a 'mixing-cutout' shape for a component.
 * </ul>
 * <p>
 * A "top-level window" is an instance of the {@code Window} class (or its
 * descendant, such as {@code JFrame}).
 * <p>
 * Some of the mentioned features may not be supported by the native platform.
 * To determine whether a particular feature is supported, the user must use
 * the {@code isTranslucencySupported()} method of the class passing a desired
 * translucency kind (a member of the {@code Translucency} enum) as an
 * argument.
 * <p>
 * The per-pixel alpha feature also requires the user to create her/his
 * windows using a translucency-capable graphics configuration.
 * The {@code isTranslucencyCapable()} method must
 * be used to verify whether any given GraphicsConfiguration supports
 * the trasnlcency effects.
 * <p>
 * <b>WARNING</b>: This class is an implementation detail and only meant
 * for limited use outside of the core platform. This API may change
 * drastically between update release, and it may even be
 * removed or be moved in some other package(s)/class(es).
 */
public final class AWTUtilities {

    
The AWTUtilities class should not be instantiated

/**
     * The AWTUtilities class should not be instantiated
     */
    private AWTUtilities() {
    }

    
Kinds of translucency supported by the underlying system.
 @see #isTranslucencySupported

/** Kinds of translucency supported by the underlying system.
     *  @see #isTranslucencySupported
     */
    public static enum Translucency {
        
Represents support in the underlying system for windows each pixel
of which is guaranteed to be either completely opaque, with
an alpha value of 1.0, or completely transparent, with an alpha
value of 0.0.

/**
         * Represents support in the underlying system for windows each pixel
         * of which is guaranteed to be either completely opaque, with
         * an alpha value of 1.0, or completely transparent, with an alpha
         * value of 0.0.
         */
        PERPIXEL_TRANSPARENT,

        
Represents support in the underlying system for windows all of
the pixels of which have the same alpha value between or including
0.0 and 1.0.

/**
         * Represents support in the underlying system for windows all of
         * the pixels of which have the same alpha value between or including
         * 0.0 and 1.0.
         */
        TRANSLUCENT,

        
Represents support in the underlying system for windows that
contain or might contain pixels with arbitrary alpha values
between and including 0.0 and 1.0.

/**
         * Represents support in the underlying system for windows that
         * contain or might contain pixels with arbitrary alpha values
         * between and including 0.0 and 1.0.
         */
        PERPIXEL_TRANSLUCENT;
    }


    
Returns whether the given level of translucency is supported by
the underlying system.
Note that this method may sometimes return the value
indicating that the particular level is supported, but
the native windowing system may still not support the
given level of translucency (due to the bugs in
the windowing system).

Params:
  • translucencyKind – a kind of translucency support
                        (either PERPIXEL_TRANSPARENT,
                        TRANSLUCENT, or PERPIXEL_TRANSLUCENT)
Returns:whether the given translucency kind is supported
/**
     * Returns whether the given level of translucency is supported by
     * the underlying system.
     *
     * Note that this method may sometimes return the value
     * indicating that the particular level is supported, but
     * the native windowing system may still not support the
     * given level of translucency (due to the bugs in
     * the windowing system).
     *
     * @param translucencyKind a kind of translucency support
     *                         (either PERPIXEL_TRANSPARENT,
     *                         TRANSLUCENT, or PERPIXEL_TRANSLUCENT)
     * @return whether the given translucency kind is supported
     */
    public static boolean isTranslucencySupported(Translucency translucencyKind) {
        switch (translucencyKind) {
            case PERPIXEL_TRANSPARENT:
                return isWindowShapingSupported();
            case TRANSLUCENT:
                return isWindowOpacitySupported();
            case PERPIXEL_TRANSLUCENT:
                return isWindowTranslucencySupported();
        }
        return false;
    }


    
Returns whether the windowing system supports changing the opacity
value of top-level windows.
Note that this method may sometimes return true, but the native
windowing system may still not support the concept of
translucency (due to the bugs in the windowing system).

/**
     * Returns whether the windowing system supports changing the opacity
     * value of top-level windows.
     * Note that this method may sometimes return true, but the native
     * windowing system may still not support the concept of
     * translucency (due to the bugs in the windowing system).
     */
    private static boolean isWindowOpacitySupported() {
        Toolkit curToolkit = Toolkit.getDefaultToolkit();
        if (!(curToolkit instanceof SunToolkit)) {
            return false;
        }
        return ((SunToolkit)curToolkit).isWindowOpacitySupported();
    }

    
Set the opacity of the window. The opacity is at the range [0..1].
Note that setting the opacity level of 0 may or may not disable
the mouse event handling on this window. This is
a platform-dependent behavior.
In order for this method to enable the translucency effect,
the isTranslucencySupported() method should indicate that the
TRANSLUCENT level of translucency is supported.

Also note that the window must not be in the full-screen mode
when setting the opacity value < 1.0f. Otherwise
the IllegalArgumentException is thrown.

Params:
  • window – the window to set the opacity level to
  • opacity – the opacity level to set to the window
Throws:
/**
     * Set the opacity of the window. The opacity is at the range [0..1].
     * Note that setting the opacity level of 0 may or may not disable
     * the mouse event handling on this window. This is
     * a platform-dependent behavior.
     *
     * In order for this method to enable the translucency effect,
     * the isTranslucencySupported() method should indicate that the
     * TRANSLUCENT level of translucency is supported.
     *
     * <p>Also note that the window must not be in the full-screen mode
     * when setting the opacity value &lt; 1.0f. Otherwise
     * the IllegalArgumentException is thrown.
     *
     * @param window the window to set the opacity level to
     * @param opacity the opacity level to set to the window
     * @throws NullPointerException if the window argument is null
     * @throws IllegalArgumentException if the opacity is out of
     *                                  the range [0..1]
     * @throws IllegalArgumentException if the window is in full screen mode,
     *                                  and the opacity is less than 1.0f
     * @throws UnsupportedOperationException if the TRANSLUCENT translucency
     *                                       kind is not supported
     */
    public static void setWindowOpacity(Window window, float opacity) {
        if (window == null) {
            throw new NullPointerException(
                    "The window argument should not be null.");
        }

        AWTAccessor.getWindowAccessor().setOpacity(window, opacity);
    }

    
Get the opacity of the window. If the opacity has not
yet being set, this method returns 1.0.

Params:
  • window – the window to get the opacity level from
Throws:
/**
     * Get the opacity of the window. If the opacity has not
     * yet being set, this method returns 1.0.
     *
     * @param window the window to get the opacity level from
     * @throws NullPointerException if the window argument is null
     */
    public static float getWindowOpacity(Window window) {
        if (window == null) {
            throw new NullPointerException(
                    "The window argument should not be null.");
        }

        return AWTAccessor.getWindowAccessor().getOpacity(window);
    }

    
Returns whether the windowing system supports changing the shape
of top-level windows.
Note that this method may sometimes return true, but the native
windowing system may still not support the concept of
shaping (due to the bugs in the windowing system).

/**
     * Returns whether the windowing system supports changing the shape
     * of top-level windows.
     * Note that this method may sometimes return true, but the native
     * windowing system may still not support the concept of
     * shaping (due to the bugs in the windowing system).
     */
    public static boolean isWindowShapingSupported() {
        Toolkit curToolkit = Toolkit.getDefaultToolkit();
        if (!(curToolkit instanceof SunToolkit)) {
            return false;
        }
        return ((SunToolkit)curToolkit).isWindowShapingSupported();
    }

    
Returns an object that implements the Shape interface and represents
the shape previously set with the call to the setWindowShape() method.
If no shape has been set yet, or the shape has been reset to null,
this method returns null.

Params:
  • window – the window to get the shape from
Throws:
Returns:the current shape of the window
/**
     * Returns an object that implements the Shape interface and represents
     * the shape previously set with the call to the setWindowShape() method.
     * If no shape has been set yet, or the shape has been reset to null,
     * this method returns null.
     *
     * @param window the window to get the shape from
     * @return the current shape of the window
     * @throws NullPointerException if the window argument is null
     */
    public static Shape getWindowShape(Window window) {
        if (window == null) {
            throw new NullPointerException(
                    "The window argument should not be null.");
        }
        return AWTAccessor.getWindowAccessor().getShape(window);
    }

    
Sets a shape for the given window.
If the shape argument is null, this methods restores
the default shape making the window rectangular.

Note that in order to set a shape, the window must be undecorated. If the window is decorated, this method ignores the shape argument and resets the shape to null. 
Also note that the window must not be in the full-screen mode
when setting a non-null shape. Otherwise the IllegalArgumentException
is thrown.

Depending on the platform, the method may return without effecting the shape of the window if the window has a non-null warning string (Window.getWarningString()). In this case the passed shape object is ignored. 
Params:
  • window – the window to set the shape to
  • shape – the shape to set to the window
Throws:
/**
     * Sets a shape for the given window.
     * If the shape argument is null, this methods restores
     * the default shape making the window rectangular.
     * <p>Note that in order to set a shape, the window must be undecorated.
     * If the window is decorated, this method ignores the {@code shape}
     * argument and resets the shape to null.
     * <p>Also note that the window must not be in the full-screen mode
     * when setting a non-null shape. Otherwise the IllegalArgumentException
     * is thrown.
     * <p>Depending on the platform, the method may return without
     * effecting the shape of the window if the window has a non-null warning
     * string ({@link Window#getWarningString()}). In this case the passed
     * shape object is ignored.
     *
     * @param window the window to set the shape to
     * @param shape the shape to set to the window
     * @throws NullPointerException if the window argument is null
     * @throws IllegalArgumentException if the window is in full screen mode,
     *                                  and the shape is not null
     * @throws UnsupportedOperationException if the PERPIXEL_TRANSPARENT
     *                                       translucency kind is not supported
     */
    public static void setWindowShape(Window window, Shape shape) {
        if (window == null) {
            throw new NullPointerException(
                    "The window argument should not be null.");
        }
        AWTAccessor.getWindowAccessor().setShape(window, shape);
    }

    private static boolean isWindowTranslucencySupported() {
        /*
         * Per-pixel alpha is supported if all the conditions are TRUE:
         *    1. The toolkit is a sort of SunToolkit
         *    2. The toolkit supports translucency in general
         *        (isWindowTranslucencySupported())
         *    3. There's at least one translucency-capable
         *        GraphicsConfiguration
         */

        Toolkit curToolkit = Toolkit.getDefaultToolkit();
        if (!(curToolkit instanceof SunToolkit)) {
            return false;
        }

        if (!((SunToolkit)curToolkit).isWindowTranslucencySupported()) {
            return false;
        }

        GraphicsEnvironment env =
            GraphicsEnvironment.getLocalGraphicsEnvironment();

        // If the default GC supports translucency return true.
        // It is important to optimize the verification this way,
        // see CR 6661196 for more details.
        if (isTranslucencyCapable(env.getDefaultScreenDevice()
                    .getDefaultConfiguration()))
        {
            return true;
        }

        // ... otherwise iterate through all the GCs.
        GraphicsDevice[] devices = env.getScreenDevices();

        for (int i = 0; i < devices.length; i++) {
            GraphicsConfiguration[] configs = devices[i].getConfigurations();
            for (int j = 0; j < configs.length; j++) {
                if (isTranslucencyCapable(configs[j])) {
                    return true;
                }
            }
        }

        return false;
    }

    
Enables the per-pixel alpha support for the given window.
Once the window becomes non-opaque (the isOpaque is set to false),
the drawing sub-system is starting to respect the alpha value of each
separate pixel. If a pixel gets painted with alpha color component
equal to zero, it becomes visually transparent, if the alpha of the
pixel is equal to 255, the pixel is fully opaque. Interim values
of the alpha color component make the pixel semi-transparent (i.e.
translucent).

Note that in order for the window to support the per-pixel alpha mode, the window must be created using the GraphicsConfiguration for which the isTranslucencyCapable method returns true. 
Also note that some native systems enable the per-pixel translucency
mode for any window created using the translucency-compatible
graphics configuration. However, it is highly recommended to always
invoke the setWindowOpaque() method for these windows, at least for
the sake of cross-platform compatibility reasons.

Also note that the window must not be in the full-screen mode
when making it non-opaque. Otherwise the IllegalArgumentException
is thrown.

If the window is a Frame or a Dialog, the window must be undecorated prior to enabling the per-pixel translucency effect (see Frame.setUndecorated() and/or Dialog.setUndecorated()). If the window becomes decorated through a subsequent call to the corresponding setUndecorated() method, the per-pixel translucency effect will be disabled and the opaque property reset to true. 
Depending on the platform, the method may return without effecting the opaque property of the window if the window has a non-null warning string (Window.getWarningString()). In this case the passed 'isOpaque' value is ignored. 
Params:
  • window – the window to set the shape to
  • isOpaque – whether the window must be opaque (true),
                or translucent (false)
Throws:
/**
     * Enables the per-pixel alpha support for the given window.
     * Once the window becomes non-opaque (the isOpaque is set to false),
     * the drawing sub-system is starting to respect the alpha value of each
     * separate pixel. If a pixel gets painted with alpha color component
     * equal to zero, it becomes visually transparent, if the alpha of the
     * pixel is equal to 255, the pixel is fully opaque. Interim values
     * of the alpha color component make the pixel semi-transparent (i.e.
     * translucent).
     * <p>Note that in order for the window to support the per-pixel alpha
     * mode, the window must be created using the GraphicsConfiguration
     * for which the {@link #isTranslucencyCapable}
     * method returns true.
     * <p>Also note that some native systems enable the per-pixel translucency
     * mode for any window created using the translucency-compatible
     * graphics configuration. However, it is highly recommended to always
     * invoke the setWindowOpaque() method for these windows, at least for
     * the sake of cross-platform compatibility reasons.
     * <p>Also note that the window must not be in the full-screen mode
     * when making it non-opaque. Otherwise the IllegalArgumentException
     * is thrown.
     * <p>If the window is a {@code Frame} or a {@code Dialog}, the window must
     * be undecorated prior to enabling the per-pixel translucency effect (see
     * {@link Frame#setUndecorated()} and/or {@link Dialog#setUndecorated()}).
     * If the window becomes decorated through a subsequent call to the
     * corresponding {@code setUndecorated()} method, the per-pixel
     * translucency effect will be disabled and the opaque property reset to
     * {@code true}.
     * <p>Depending on the platform, the method may return without
     * effecting the opaque property of the window if the window has a non-null
     * warning string ({@link Window#getWarningString()}). In this case
     * the passed 'isOpaque' value is ignored.
     *
     * @param window the window to set the shape to
     * @param isOpaque whether the window must be opaque (true),
     *                 or translucent (false)
     * @throws NullPointerException if the window argument is null
     * @throws IllegalArgumentException if the window uses
     *                                  a GraphicsConfiguration for which the
     *                                  {@code isTranslucencyCapable()}
     *                                  method returns false
     * @throws IllegalArgumentException if the window is in full screen mode,
     *                                  and the isOpaque is false
     * @throws IllegalArgumentException if the window is decorated and the
     * isOpaque argument is {@code false}.
     * @throws UnsupportedOperationException if the PERPIXEL_TRANSLUCENT
     *                                       translucency kind is not supported
     */
    public static void setWindowOpaque(Window window, boolean isOpaque) {
        if (window == null) {
            throw new NullPointerException(
                    "The window argument should not be null.");
        }
        if (!isOpaque && !isTranslucencySupported(Translucency.PERPIXEL_TRANSLUCENT)) {
            throw new UnsupportedOperationException(
                    "The PERPIXEL_TRANSLUCENT translucency kind is not supported");
        }
        AWTAccessor.getWindowAccessor().setOpaque(window, isOpaque);
    }

    
Returns whether the window is opaque or translucent.

Params:
  • window – the window to set the shape to
Throws:
Returns:whether the window is currently opaque (true)
        or translucent (false)
/**
     * Returns whether the window is opaque or translucent.
     *
     * @param window the window to set the shape to
     * @return whether the window is currently opaque (true)
     *         or translucent (false)
     * @throws NullPointerException if the window argument is null
     */
    public static boolean isWindowOpaque(Window window) {
        if (window == null) {
            throw new NullPointerException(
                    "The window argument should not be null.");
        }

        return window.isOpaque();
    }

    
Verifies whether a given GraphicsConfiguration supports the PERPIXEL_TRANSLUCENT kind of translucency. All windows that are intended to be used with the setWindowOpaque method must be created using a GraphicsConfiguration for which this method returns true. 
Note that some native systems enable the per-pixel translucency
mode for any window created using a translucency-capable
graphics configuration. However, it is highly recommended to always
invoke the setWindowOpaque() method for these windows, at least
for the sake of cross-platform compatibility reasons.

Params:
  • gc – GraphicsConfiguration
Throws:
Returns:whether the given GraphicsConfiguration supports
        the translucency effects.
/**
     * Verifies whether a given GraphicsConfiguration supports
     * the PERPIXEL_TRANSLUCENT kind of translucency.
     * All windows that are intended to be used with the {@link #setWindowOpaque}
     * method must be created using a GraphicsConfiguration for which this method
     * returns true.
     * <p>Note that some native systems enable the per-pixel translucency
     * mode for any window created using a translucency-capable
     * graphics configuration. However, it is highly recommended to always
     * invoke the setWindowOpaque() method for these windows, at least
     * for the sake of cross-platform compatibility reasons.
     *
     * @param gc GraphicsConfiguration
     * @throws NullPointerException if the gc argument is null
     * @return whether the given GraphicsConfiguration supports
     *         the translucency effects.
     */
    public static boolean isTranslucencyCapable(GraphicsConfiguration gc) {
        if (gc == null) {
            throw new NullPointerException("The gc argument should not be null");
        }
        /*
        return gc.isTranslucencyCapable();
        */
        Toolkit curToolkit = Toolkit.getDefaultToolkit();
        if (!(curToolkit instanceof SunToolkit)) {
            return false;
        }
        return ((SunToolkit)curToolkit).isTranslucencyCapable(gc);
    }

    
Sets a 'mixing-cutout' shape for the given component.
By default a lightweight component is treated as an opaque rectangle for
the purposes of the Heavyweight/Lightweight Components Mixing feature.
This method enables developers to set an arbitrary shape to be cut out
from heavyweight components positioned underneath the lightweight
component in the z-order.

 The shape argument may have the following values: 
    

  • null - reverts the default cutout shape (the rectangle equal to the component's getBounds()) 
  • empty-shape - does not cut out anything from heavyweight
components. This makes the given lightweight component effectively
transparent. Note that descendants of the lightweight component still
affect the shapes of heavyweight components.  An example of an
empty-shape is new Rectangle(). 
  • non-empty-shape - the given shape will be cut out from
heavyweight components.



 The most common example when the 'mixing-cutout' shape is needed is a glass pane component. The setGlassPane.setGlassPane() method automatically sets the empty-shape as the 'mixing-cutout' shape
for the given glass pane component.  If a developer needs some other
'mixing-cutout' shape for the glass pane (which is rare), this must be
changed manually after installing the glass pane to the root pane.


Note that the 'mixing-cutout' shape neither affects painting, nor the
mouse events handling for the given component. It is used exclusively
for the purposes of the Heavyweight/Lightweight Components Mixing
feature.

Params:
  • component – the component that needs non-default
'mixing-cutout' shape
  • shape – the new 'mixing-cutout' shape
Throws:
/**
     * Sets a 'mixing-cutout' shape for the given component.
     *
     * By default a lightweight component is treated as an opaque rectangle for
     * the purposes of the Heavyweight/Lightweight Components Mixing feature.
     * This method enables developers to set an arbitrary shape to be cut out
     * from heavyweight components positioned underneath the lightweight
     * component in the z-order.
     * <p>
     * The {@code shape} argument may have the following values:
     * <ul>
     * <li>{@code null} - reverts the default cutout shape (the rectangle equal
     * to the component's {@code getBounds()})
     * <li><i>empty-shape</i> - does not cut out anything from heavyweight
     * components. This makes the given lightweight component effectively
     * transparent. Note that descendants of the lightweight component still
     * affect the shapes of heavyweight components.  An example of an
     * <i>empty-shape</i> is {@code new Rectangle()}.
     * <li><i>non-empty-shape</i> - the given shape will be cut out from
     * heavyweight components.
     * </ul>
     * <p>
     * The most common example when the 'mixing-cutout' shape is needed is a
     * glass pane component. The {@link JRootPane#setGlassPane()} method
     * automatically sets the <i>empty-shape</i> as the 'mixing-cutout' shape
     * for the given glass pane component.  If a developer needs some other
     * 'mixing-cutout' shape for the glass pane (which is rare), this must be
     * changed manually after installing the glass pane to the root pane.
     * <p>
     * Note that the 'mixing-cutout' shape neither affects painting, nor the
     * mouse events handling for the given component. It is used exclusively
     * for the purposes of the Heavyweight/Lightweight Components Mixing
     * feature.
     *
     * @param component the component that needs non-default
     * 'mixing-cutout' shape
     * @param shape the new 'mixing-cutout' shape
     * @throws NullPointerException if the component argument is {@code null}
     */
    public static void setComponentMixingCutoutShape(Component component,
            Shape shape)
    {
        if (component == null) {
            throw new NullPointerException(
                    "The component argument should not be null.");
        }

        AWTAccessor.getComponentAccessor().setMixingCutoutShape(component,
                shape);
    }
}